Field of the Invention
The present invention relates to a method for manufacturing a transparent electrode, a transparent electrode, and an organic electroluminescent device provided with the same, and more specifically to a method for manufacturing a transparent electrode using a coating or printing method.
Discussion of the Background
In recent years, the research and development of light emitting apparatuses provided with light emitting device type display panels is being underway. In such a light emitting device type display panel, self-luminous devices, such as organic electroluminescent devices (hereinafter referred to as “organic EL devices”), as the next-generation display devices are two-dimensionally arrayed.
The organic EL device includes an anode, a cathode, and an organic EL layer (light emitting functional layer) formed between the anode and the cathode in a pair. The organic EL layer includes an organic light emitting layer, a hole injection layer, and the like, for example. The organic EL device emits light with the energy generated by recombination of a hole and an electron in the organic light emitting layer.
Such an organic EL device has a light extraction side transparent electrode which is formed, generally, using tin doped indium oxide (indium tin oxide: ITO), zinc doped indium oxide (indium zinc oxide: IZO), or the like. However, in the case where a transparent electrode is formed using these materials, a thick and uniform film has to be formed to obtain a low resistance. Consequently, the light transmission of the transparent electrode is likely to be decreased, or products provided with the transparent electrode are likely to be expensive. In addition, the processes for forming a transparent electrode sometimes involve high temperature processing. For this reason, there have been limitations in decreasing the resistance of a transparent electrode on a film, in particular (e.g. see Patent Literature 1).
For the above transparent electrode, in recent years, transparent electrode techniques without using indium oxides, such as ITO, have been developed and disclosed. For example, for a method for forming a transparent electrode without using indium oxides, such as ITO, the following method is proposed (e.g. see Patent Literatures 2 and 3). In the method, a conductive surface is prepared, first, which is arranged with a thin wire structure made of a metal and/or an alloy and in a uniform mesh, comb or grid shape. Subsequently, on the conductive surface, an ink, in which a conductive polymeric material is dissolved or dispersed in a suitable solvent, for example, is coated using a coating or printing method to form a transparent conductive layer. Thus, a transparent electrode is formed without using indium oxides, such as ITO.
Patent Literature 1: JP-A-H10-162961
Patent Literature 2: JP-A-2005-302508
Patent Literature 3: JP-A-2006-093123